managing database with thousands of tables

Hello!

I facing some strange problems with PostgreSQL 8.0 performance.
I have application which handles a lot of tasks, each task is keps in separate
table. Those tables are dropped and created again periodically (precisely -
when new task results came back from remote server). Also each table can have
hundreds of thousands records inside (but mostly they do have just few
thousands).

Sometimes I facing performance loss when working with database, and aafter I
performed vacuuming on entire database, i saw some tables and indexes in pg_*
schemas were optimized and hundreds of thousands records were deleted. Could
that be the reason of performance loss, and if so - how can I fix that?

I have pg_autovacuum up and running all the time

pg_autovacuum -d 3 -D -L /dev/null

but it seems pg_autovacuum does not do vacuuming on system tables.

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Eugene Dzhurinsky